1. Field of the Invention
The present invention relates to a starting method and a device therefor for starting the operation of a coal gasifier in which pulverized coal is charged into the furnace by means of inert transfer-gas (carrier-gas); more in detail, the invention relates to a starting method preferred for starting the operation of the coal gasifier by means of flammable gas, and a device for enforcing the starting method.
2. Background of the Invention
In a coal gasifier of a pressurized two-stage entrained-bed type and an air blowing type the furnace which includes a combustor and a reductor; the ash content in the coal as fuel is melted; vitreous slag is formed in the furnace and discharged therefrom; thus, the inner wall of the furnace in operation is covered with the melted slag. Hence, in a case where a starting burner for starting the operation of the furnace is provided at the combustor side of the furnace, the tip part of the starting burner the part which protrudes toward the furnace inside is covered with the slag when the starting burner is stopped and the operation of the furnace is stopped for a long duration of time before the next operation; thus, the restart of the furnace operation becomes difficult; therefore, the starting burner is needed to be, as it used to be, placed at a starting combustion chamber that is provided independently from the combustor.
FIG. 6 as an example shows a basic configuration as to the starting system for the conventional coal gasifier. As shown in FIG. 6, a coal gasifier 02 comprises a pressure vessel that is provided with a combustor 03 at the inner lower side of the furnace, a reductor burner 04 at the upper side of the combustor 03, and a warm-up burner 06 at the lower side of the combustor burner 03 as well as at the lower side of a slag tap 05.
The coal (pulverized coal) that is transferred by nitrogen gas (carrier gas) through the fuel supply passage 08 as well as air is thrown into a combustor 07 inside the coal gasifier 02 via the combustor burner; thereby, in the furnace, hot combustion gas is generated mainly by the combustion of the coal. Further, the melting slag is formed, being separated from the hot combustion gas; some part of the slag adheres to the inner wall inside the furnace and drops down along the wall; and some part of the slag directly drops down to the bottom of the furnace. Thus, the generated slag is discharged downward through the slag tap 05.
In addition, below the slag tap 05, cooling water 09 for cooling the discharged slag through the slag tap is stored
Also via a reductor burner 04 that is placed over the combustor burner 03, the coal (pulverized coal) that is transferred by nitrogen gas (carrier gas) as well as air through the fuel supply passage 010 is thrown into a reductor 011 arranged inside the coal gasifier 02. In the reductor 011, the coal is mixed with the hot gas, and a coal gasification reaction is performed in a reducing atmosphere so as to yield flammable gas.
In starting the operation of the coal gasifier 02, the warm-up burner 06 is used; thereby, auxiliary fuel for warming-up the furnace as well as air or oxygen is supplied to the warm-up burner 06 through which the auxiliary fuel as well as air or oxygen is thrown into a start-up combustion chamber 012 arranged inside the coal gasifier 02. The heat produced by the combustion reaction between the auxiliary fuel and air-or-oxygen warms up the inside of the coal gasifier 02; after the temperature inside the furnace 02 exceeds the ignition temperature of the pulverized coal, the pulverized coal together with air is thrown into the combustor 07 via the combustor burner 03; at the same time, the supply of the auxiliary fuel for warm-up is stopped.
The subject is now changed into the conventional technology. The patent reference 1 (JP2002-161283) discloses a method for starting-up the coal gasifier.
As shown in FIG. 7 of this application, the furnace according to the patent reference 1 comprises:                a coal gasifier (a furnace body) 020;        a coal burner 022 and a coal burner 023 that are provided at the coal gasifier 020, thereby pulverized coal and oxygen are supplied to a furnace-inside 021 in the furnace body via the burners 022 and 023, and the pulverized coal is burned so that the furnace-inside 021 is heated up and the coal is gasified;        a slag tap 024 that is provided at the lower side of the coal burner 023, thereby the melted slag is discharged via the slag tap 024;        a tap burner 025 that is provided at the lower side of the slag tap 024, thereby the tap burner heats up the slag tap 024.        
In the case of starting the operation of the coal gasifier, before pulverized coal is supplied toward the coal burners 022 and 023, the coal through the tap burner 025 is burned so as to heat up the slag tap 025 and raise the temperature of the furnace-inside 021.
However, as shown in FIG. 6, in the warm-up burner (the start-up burner) 06 of the conventional technology, it is needed that a start-up combustion chamber 012 is provided at the lower side of the combustor 07 in the coal gasification (melting) furnace 02, and the warm-up burner 06 is arranged there; thus, the height of the whole coal gasification furnace 02 increases, and the whole system is upsized; further, the number of the stand-pipes that surrounds and configures the pressure vessel 02 also increases; as a result, the manufacturing cost of the furnace increases.
In addition, according to the disclosed technology of the patent reference as is the case with the above conventional technology; the tap burner needs to be placed below the slag tap; thus, the height of the coal gasifier is increased, the pressure vessel is upsized, and the manufacturing cost of the furnace is increased.